Conversely, following infection with a Listeria monocytogenes engineered to secrete the LCMV GP61–80 epitope (Lm-gp61), SMARTA cells developed sub-optimal effector function as compared to polyclonal endogenous CD4+ T cell responders to the same epitope in the same host, exemplified by decreased antigen sensitivity and lower cytokine production, and failed to populate the memory pool [14]. Here, CD4 is linked to infection.